The present invention relates to saws. More particularly, it relates to medical and orthopedic saws in which the blades move in an orbital fashion at the work end.
Medical and orthopedic saws are generally hand held. Some are manually operated. Some are electrically or pneumatically operated. It is known to use such saws to remove fracture casts, to saw bones and to perform other medical and orthopedic procedures by using different saw blades.
U.S. Pat. No. 3,905,105 describes such an orthopedic bone saw. It has a blade carrier and a separate blade. The blade carrier includes a first end portion and an intermediate portion housed in a casing and a second end portion projecting from the casing. The first end portion is coupled with an eccentric, rotary drive spindle. The intermediate portion is constrained by the casing for longitudinal translation and pivotal movement. A blade is connected with the second end portion. When the saw is energized, each point along the free end of the blade moves in an elliptical path.
The blade carrier is a permanent part of the saw. In use, considerable pressure may be applied to the bearing points between the casing and the carrier resulting in wear and eventual failure of the blade carrier. To afford a longer life, it is believed the blade carrier disclosed in U.S. Pat. No. 3,905,105 must be relatively heavy and bulky in construction and well lubricated to reduce wear. Also, it should be protected from foreign materials, as recited in the patent, to extend its useful life. This is said to be accomplished by piston-like blocks in the area where the blade carrier emerges from the casing. As disclosed, the portions of the blade carrier where wear may occur are housed within the hollow casing. This additional casing and relatively heavy blade carrier add weight to the saw. This is both expensive and burdensome in a hand-held device.